There were quite a few titles that continued to use 16-bit Windows 3.1 binaries well past 1998 and in to the 2000s. Sometimes they didn't even advertise compatibly with Windows 3.1.

Since Windows 9x was built on top of 3.1, it ran 3.1 binaries natively (unlike NT that had to use a VDM), so it was sometimes hard to even tell if something was 16-bit or 32-bit unless you examined the EXE file.

That is why there is still such a need for the 32-bit versions of Windows that support 16-bit binaries. I'm still rather surprised how the 64-bit versions took off without a larger backlash.